A 64-year-old woman with blurred vision and a headache had giant cell arteritis despite ESR and CRP well within normal ranges.
McAlinden C, Ioannidis P, Roberts S, and Skiadaresi E. Giant cell arteritis. Lancet (2014) 383:1182, Mar. 29, 2014
This case study is a reminder that normal erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) do not rule out giant cell arteritis.
A 64-year-old woman presented to her optometrist with blurred vision in the left eye and a left-sided headache. She had a swollen optic disk in the left eye. Within four hours, the vision had been reduced to hand movements.
CRP was 7 mg/L (local normal range 0-20) and ESR was 14 mm/h (local normal range 0-20).
Because of the abnormal presentation, she was started on oral prednisolone 60 mg daily, until a temporal artery biopsy confirmed the diagnosis five days later.
Four percent of patients with giant cell arteritis present with CRP and ESR in normal ranges. If giant cell arteritis is suspected on clinical grounds, a temporal artery biopsy should be done despite the normal labs.